Speed detector

ABSTRACT

A device for producing a signal when, for example, a rotating body reaches a predetermined velocity. For example, a telegraphic printer will print with an unwanted orientation or in an undesired way if printing is permitted during start up of the mechanism. The device disclosed herein may thus be employed to inhibit printing until the mechanism gets up to speed.

United States Patent Gane June 26, 1973 SPEED DETECTOR [5 6] References Cited [75] Inventor: Alan Ernest Gane, Burgess Hill. UNITED STATES PATENTS England 3,500,375 7/1970 Klimo 324/l86 x [73] Assignee: International Standard Electric I Corporation, New York, NY. Primary Exammer-J. D. Miller Assistant ExaminerHarry E. Moose, Jr. [22] led: l 1972 Attorney-C. Cornell Remsen .Ir., Thomas 211 App], 2 ,572 Kristofferson et al.

57 ABSTRA [30] Foreign Application Priority Data 1 CT Oct 7 197] En and 46 704/71 A device for producing a signal when, for example, a g rotating body reaches a predetermined velocity. For

example, a telegraphic printer will print with an un- [521 Cl 317/5 303/21 gag 3 wanted orientation or in an undesired way if printing is {51 1 In Cl 02 7/00 permitted during start up of the mechanism. The device [58] Fie'ld 173 disclosed herein may thus be employed to inhibit print- 324/186; 317/5, 19; 303/21 CE, 21C, 2 CF; 307/233; 340/263 ing until the mechanism gets up to speed.

2 Claims, 1 Drawing Figure PATENTED JUN 2 6 I915 I I I .J

1 l4 A l SPEED DETECTOR BACKGROUND OF THE INVENTION This invention relates to a speed sensing arrangement for a printing telegraph machine or the like. Such a machine incorporates a print wheel or cylinder which rotates continuously, at least during printing.

It is usual in such machines that during idle periods, when messages are neither being generated at the machine nor received by it, the motor which drives all the mechanical parts is shut down. This usually occurs after a short period of idleness has been measured by a suitable device. However, the machine is always kept in readiness and the motor is started up the moment a genuine start signal arrives on the incoming line. The motor will quickly reach its working or full speed but during the time that it is doing so, care must be taken not to print inadvertently because the time of flight of the printing hammer is designed to work with a printing wheel revolving at full speed.

SUMMARY OF THE INVENTION The invention provides one way of ensuring that the motor is at full speed before any printing action can take place.

According to the present invention, there is provided an on-speed sensing arrangement for a printing telegraph machine, which machine incorporates a continuously rotating print-wheel, including a toothed index wheel which is arranged to rotate in synchronism with the print-wheel, a sensor for producing an impulse each time a tooth passes it, and an electronic frequency sensing device which is set in operation by each impulse of a first train of alternate impulses from the sensor, and halted by each impulse of a second train of alternate impulses from the sensor, the frequency sensing device producing an inhibiting signal to hold the printing mechanism of the machine inoperative if it reaches a predetermined state before being halted by an impulse of said second train.

BRIEF DESCRIPTION OF THE DRAWING An embodiment of the invention is described below with reference to the accompanying drawing which shows schematically the components and circuit of an on-speed sensing arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENT A motor 1 drives a print-wheel 2 mounted on a shaft 3. Also on the shaft, or geared to it so as to rotate in synchronism, is a toothed index wheel 4. A sensor 5, here represented as a magnetic pick-up, senses the passage of each tooth as the wheel 2 revolves and produces a train of corresponding impulses. The train of impulses are applied over line 7 to an electronic frequency sensing device 8 which produces an inhibiting signal on line 9 as long as the input frequency on line 7 is less than a desired value.

A variety of electronic frequency sensing devices can be devised but one which is readily resettable and can have as fine a resolution as desired includes in combination a toggle 10 used as a scale-of-two circuit to which the input impulses are applied, a counting circuit 1l, an oscillator 12 which supplies impulses to one input of an AND gate 13, an output toggle 14 set by an output from the last stage of the counter, or from the combined (ORed) output from a particular combination of stages, and cleared by way of AND gate 15. Alternate impulses on line 7 turn on the A side of toggle 10. This, applied to the other input of gate 13, opens the gate and allows the impulses from oscillator 12 to drive the counter 11. If the wheels 2 and 4 are running too slowly, the counter will reach its predetermined count before a succeeding impulse on line 7 returns on the B side of toggle l0, and will set toggle 14 to its A side, thus producing the inhibiting signal on line 9, and at the same time it will inhibit gate 15 so that the subsequent turning on of the B side of toggle 10 will not interrupt the inhibit signal on line 9 by clearing the toggle 14. When, however, the wheels reach full speed, then the B side of toggle 10 will be turned on just before counter 11 reaches its predetermined count, and will clear both counter 11 and toggle 14. After that, the counter will not be able to reach its predetermined count and set toggle 14 until the motor is shut down in the next idle period, assuming, of course, that the machine is in good running order so that nothing causes serious variation of the speed of the wheels 2 and 4.

It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation on its scope.

What is claimed is:

1. A control system comprising: a member movable in a predetermined direction; means fixed adjacent said member to produce output pulses at a pulse repetition frequency (PRF) directly proportional to the velocity of said member; a first flip-flop connected from said means in a manner to change states each time said means produces one of said output pulses thereof, said first flip-flop having A and B sides; a burst oscillator; a pulse counter; a second flip-flop having A and B sides; a first AND gate; and a second AND gate, said first AND gate being connected from said first flip-flop A side and from said oscillator to the input of said counter, the B side of said first flip-flop being connected to said counter to reset the same, said second AND gate being connected from the output of said counter and from the B side of said first flip-flop to the B side of said second flip-flop, the output of said counter being connected to the input of the A side of said second flip-flop, the two levels of output of the A side of said second flip-flop being respectively representative of whether the speed of said member is above or below a predetermined speed.

2. The invention as defined in claim 1, wherein said member is a rotatable toothed ferromagnetic wheel,

said means including a ferromagnetic pick-up. 

1. A control system comprising: a member movable in a predetermined direction; means fixed adjacent said member to produce output pulses at a pulse repetition frequency (PRF) directly proportional to the velocity of said member; a first flip-flop connected from said means in a manner to change states each time said means produces one of said output pulses thereof, said first flip-flop having A and B sides; a burst oscillator; a pulse counter; a second flip-flop having A and B sides; a first AND gate; and a second AND gate, said first AND gate being connected from said first flip-flop A side and from said oscillator to the input of said counter, the B side of said first flip-flop being connected to said counter to reset the same, said second AND gate being connected from the output of said counter and from the B side of said first flip-flop to the B side of said second flip-flop, the output of said counter being connected to the input of the A side of said second flip-flop, the two levels of output of the A side of said second flip-flop being respectively representative of whether the speed of said member is above or below a predetermined speed.
 2. The invention as defined in claim 1, wherein said member is a rotatable toothed ferromagnetic wheel, said means including a ferromagnetic pick-up. 